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Citrus Canker

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Citrus canker is a disease caused by the bacterium Xanthomonas citri subsp. citri

(synonym X. axonopodis pv. citri). It thrives in areas with high rainfall and warm

temperatures. Citrus canker is found throughout Florida and in limited areas of

Alabama, Louisiana, and Texas. Severely infected citrus trees may lose their leaves

and prematurely drop fruit. Canker-infected fruit is safe to eat but is not marketable

due to its appearance.
The bacteria that cause canker can enter tree leaves naturally or through wounds

caused by weather or insects, such as the citrus leaf miner (Phyllocnistis citrella

Stainton). It can survive for months on plant surfaces. Young leaves, stems, and

developing fruit are most susceptible to the disease. The disease is spread by wind

and rain and by people moving contaminated equipment, untreated infected fruit,

and infected plants and clippings.

What To Look For

Raised brown lesions with water-soaked edges and a yellow halo on fruit,

leaves, or stems

Older lesions may lose the yellow halo and appear corky

View symptoms in our citrus canker photo gallery.

How To Prevent This Disease

Know the quarantines in your area.

Buy only USDA-certified citrus plants.

Don't move branches, green waste, dead trees, and other regulated items out

of a quarantined area.

Do not mail or transport home-grown citrus fruit or plants out of a quarantined

area.

Commercial nurseries must follow strict protocols for moving citrus nursery

stock (227.22 KB) out of quarantined areas.

How It Is Treated

There is no treatment or cure for citrus canker. Infected trees continually decline

and eventually stop producing fruit.

Report Signs of Citrus Disease
If you think you've seen signs of this disease or pest, immediately report it by

completing our online form.

Report Form (English)

Report Form (Spanish)

Controlling Citrus Canker

History of Citrus Canker in the United States

Citrus canker was first identified in the United States near the Florida-Georgia border

in 1910. It took 21 years and the destruction of 257,745 grove trees and 3,093,110

nursery trees to eradicate the disease.

In 1995, canker was again discovered in Miami-Dade County, FL. Despite a 10-year

effort to eradicate the disease, a series of unprecedented storms in 2004 and 2005

spread the disease to the point where eradication was no longer possible. The

Secretary of Agriculture officially called an end to eradication efforts in 2006. He

directed that work shift to containing the disease and establishing criteria under

which fruit and nursery stock could safely move out of Florida.

Citrus canker was later found in Louisiana in 2013, in Texas in 2016, and in Alabama

in 2021. APHIS is working with partners to contain the disease in these States.

Current Quarantine Boundaries

APHIS publishes the legal description of current quarantine areas. Users can search

by State and pest to determine quarantine area(s).

Table of Federal Quarantine Descriptions

Interactive Citrus Federal Quarantine Map

Regulations

Interstate Movement of Regulated Fruit from a Quarantine Area (7 CFR 301.75)

Regulated Articles Table: Use this table to find requirements for moving

regulated articles, such as fruit, nursery stock, and other items.

APHIS Treatment Manual for Fresh Fruit

Potentially Actionable Suspect Sample Policy
A potentially actionable suspect sample (PASS) is a regulatory sample3 from the

environment or an APHIS-approved exclusionary facility5 where preliminary

diagnostics indicate that Xanthomonas spp.*, a USDA-regulated pathogen, is present

and must be confirmed by APHIS' Plant Pathogen Confirmatory Diagnostics

Laboratory (PPCDL).

Samples Collected from a Non-Regulated Area

Any regulatory sample collected from a non-regulated area1 or APHISapproved exclusionary facility that tests positive using APHIS-approved tests for

the presence of Xanthomonas spp., the causative agent for citrus canker, is

considered a PASS and must be forwarded to PPCDL for final determination. A

sample4 should consist of symptomatic plant material (leaves, twigs, or/and fruit).

Sample Diagnostics

USDA APHIS PPQ Science & Technology

Plant Pathogen Confirmatory Diagnostics Laboratory

9901 Powder Mill Rd. Bldg. 580

Laurel, MD 20708

Phone: 301-313-9208 or 301-313-9271

When forwarding materials, notify the lab by email (APHISPPQCPHSTBeltsvilleSampleDiagnostics@usda.gov). Include the number of samples,

screening diagnostic results, and tracking information in this communication. Do not

ship samples on Fridays or the day before a federal holiday.

Please see additional information for preparing and submitting samples.

Samples Collected from a Regulated Area

A regulatory sample collected in a regulated area2 where preliminary

diagnostics indicate Xanthomonas spp. is considered a PASS and requires

confirmation by PPCDL ONLY under the following conditions:

The sample is an unusual detection (novel symptoms or new host), and/or

The sample will result in the expansion of a previously established regulated

area
If neither of these conditions apply, the sample should be evaluated by the Statedesignated laboratory or forwarded to the PPQ Domestic Identification Plant

Pathology Lab for final determination.

PPQ Domestic Identification Plant Pathology Lab

USDA APHIS PPQ Kansas State University

4024 Throckmorton Plant Sciences Center

Manhattan, KS 66506

Phone: 785-532-1349

ppq.ops.ks.manhattan.lab@usda.gov

You must notify APHIS laboratories and the APHIS Domestic Diagnostics Coordinator

(ppq.domestic.diagnostic.doordinator@usda.gov) of the suspect positive sample for

which confirmation is being requested before shipping samples.

Definitions

1 Non-Regulated Area: Any area where citrus canker is not known to occur in the

United States.

2 Regulated Area: Any APHIS-recognized area where citrus canker has been

federally confirmed.

3 Regulatory Sample: This is a sample of regulatory concern to APHIS for citrus

canker collected by regulatory officials.

4 Sample: A sample refers to a single bag of leaves or a twig with attached leaves.

Each sample is to contain 5 to 12 symptomatic leaves, if possible. We strongly

recommend that each sample is from a single plant. Fruit or twigs without leaves

could be collected if leaves are not available. In addition to the plant sample, an

inactivated (boiled) bacterial streaming suspension prepared according to the WI-BT-2-2 can be submitted.

5 APHIS-approved exclusionary facility: A greenhouse structure designed to

exclude quarantine pests that is approved by APHIS to produce citrus nursey stock

for interstate movement.

*Xanthomonas spp. refers to 1) Xanthomonas axonopodis pv. citri (Xac A, A* and

AW) with synonyms X. citri pv. citri, or X. citri subsp. citri or X. campestris pv. citri or

X. smithii subsp.citri and 2) X. axonopodis pv. aurantifolii (Xac B & C) with a
synonym X. fuscans subsp. aurantifolii.